periderm

the outermost layer of flattened epidermis on an embryo or fetus during the first 6 months of gestation.

periderm

A transiently expressed superficial layer that surrounds the developing epidermis.

per·i·derm

, periderma (per'i-dĕrm, -dĕr'mă)

The outermost layer of the epidermis of the embryo and fetus up to the sixth month of intrauterine life; desquamated epitrichial cells are a considerable component of the vernix caseosa. Synonym(s): epitrichium.

[peri- + G. derma, skin]

periderm

a protective tissue formed in roots and stems that has undergone SECONDARY THICKENING, consisting of an outer cork zone, an underlying phellogen (cork cambium) and with a phelloderm (secondary cortex) beneath that.

periderm

the outer layer of the bilaminar fetal epidermis, generally disappearing before birth. Called also epitrichium.

The metaphyll's petiole shows similarity with the eophyll, except for the presence of trichomes, periderm on both sides (mainly at the base and on the adaxial side), idioblasts with druses, and primordium fibers on the phloematic region.

Values for maximum crushing strength could not be obtained under the conditions employed since the spongy obliterated phloem tissues between the periderm tissues were so weak, and failed continuously, that an abrupt mechanical failure could not be recorded.

The permeability of the skin of the tuber is a function of its maturity and is significant in the rate of respiration for example the periderm of freshly harvested immature tubers is most permeable and thus permits higher levels of respiration than similarly harvested mature tubers.

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